A packet video/audio system using the asynchronous transfer mode technique

A description is given of a prototype point-to-point packet transmission system which integrates a fixed-bit-rate PCM coded NTS quality video signal and two multiplexed audio channels for broadband integrated services digital network (B-ISDN) service. The system contains an assembler interface card at the transmit end and a disassembler interface card at the receive end. At the assembler interface card, service equipment is connected in a daisy-chained architecture. Information is integrated into a SONET-like asynchronous transfer mode (ATM) data stream. At the disassembler interface card incoming information is broadcast to each piece of receive service equipment. Only information addressed to the equipment is filtered out. Service clock information which is not carried by the network is recovered by the receive equipment using a digital phase-locked loop. The framing, deframing and multiplexing of services were facilitated by using Bellcore´s custom-designed CMOS Framer chips. This system provides a broadband service multiplexer and demultiplexer capable of integrating high-bandwidth services such as full motion video, and lower bit-rate services (e.g. audio) using a uniform system structure. The ATM technique as well as the cell headers used in this prototype are also discussed